Why Do Tolerance and Escalation Develop?

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David Fawcett PhD, LCSW

As stated in my previous post, tolerance and escalation are common signs of addiction. Tolerance occurs when the body requires increasingly larger or more potent doses to get the same effect from an addictive substance or a behavior. Escalation occurs when a person indulges his or her tolerance to an addictive substance or behavior with larger or more potent doses and/or behaviors that result in higher intensity. Almost every addict, regardless of the nature of his or her addiction, will experience some degree of tolerance and escalation.

Tolerance and escalation are a straightforward function of brain chemistry and neuroplasticity (adapting to changing circumstances).

In a non-addicted brain, the nucleus accumbens (the brain’s ‘reward center’) responds to naturally occurring, life-affirming stimuli (eating, relaxing, helping others, achieving success, being sexual, etc.) with feelings of pleasure and contentment. These feelings arise related to the release and reception of various neurochemicals in the brain – most notably dopamine, but also adrenaline, oxytocin, serotonin, and a few others.

For an easy to understand (and greatly simplified) example, consider a tasty meal. Eating good food causes dopamine-producing neurons to release dopamine into the nucleus accumbens. Once released, this dopamine attaches to dopamine-receptor neurons, creating the sensation of pleasure. (The experience of pleasure doesn’t happen until dopamine ‘plugs in’ to a receptor.) Eating and similarly life-affirming activities are rewarded in this way because they ensure survival of both the individual and the species. If we feel pleasure when we do something, we’re more likely to do it again. This is intelligent design at its finest.

Unfortunately, the brain’s reward center can be manipulated by artificial stimuli. The easiest way to do this is to ingest an addictive substance (nicotine, alcohol, cocaine, heroin, etc.) or to engage in a pleasurable and highly intense – and therefore potentially addictive – behavior (gambling, spending, non-intimate sex, porn, etc.) Typically, these substances and behaviors flood the brain with two to ten times the level of dopamine we see with naturally occurring stimuli.

Is it any wonder that some of us choose to use addictive substances and behaviors as a coping mechanism, used over and over and over to fend off stress, anxiety, loneliness, boredom, shame, depression, and other forms of emotional discomfort?

As we repeatedly flood the reward system with dopamine, the brain, which is surprisingly plastic (malleable), adapts. Basically, the brain alters itself in response to external inputs. When our use of addictive substances and behaviors continually floods the reward center with dopamine, the brain responds by reducing the number of neurons that produce and release dopamine, and by reducing the number of neurons that receive and process dopamine. The brain recognizes an abnormality – too much dopamine – and heals itself in ways that reduce the impact.

In this way, the brain continually ‘turns down the volume’ on addictive substances and behaviors. Therefore, the amount of stimulation that got a person high when he or she first started using no longer gets the job done. This is tolerance. And in response to tolerance, the user will escalate, especially when addiction sets in. This is true with both addictive substances and behaviors because the neurochemical reaction – the dopamine response – is the same either way.

Again, this is a highly simplified explanation of what happens in the brain when we ingest addictive substances or engage in addictive behaviors. Other neurochemicals are involved, but since dopamine is the primary form of ‘pleasure juice’ related to the formation and maintenance of addiction, this discussion has focused on dopamine.

With sexualized drug use – the pairing/fusion of sex and drug behaviors – the neurochemical reaction and response described above is intensified. The co-occurring use of addictive substances and addictive sexual behaviors pumps up the release and reception of dopamine to incredible levels, and, in response, the brain shuts down its ability to process dopamine to a very severe extent.

Unfortunately, this ‘turning down the volume’ process impacts more than just substance use and sexual behaviors. All aspects of life are affected. Chocolate cake tastes like cardboard. Spending time with a spouse or children feels empty. Will Ferrell is no longer funny. This (thankfully temporary) inability to experience pleasure is known as anhedonia. When the addict steps away from his or her addiction and stays away for a period of time – typically six to eighteen months – the reward center will gradually return to baseline and pleasure can once again be experienced.

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If you or someone you care about is struggling with sex, porn, or substance/sex addiction, Seeking Integrity can help with residential treatment and online workgroups. We also provide a variety of free resources (webinars, drop-in discussion groups, podcasts, blogs, daily inspirations, and more) through our SexandRelationshipHealing.com website.